Alzheimer's disease is a common form of age-related dementia that causes gradual loss of cognitive function, including memory and critical thinking abilities. Alzheimer's disease is diagnosed clinically by through a finding of progressive memory loss and decrease in cognitive abilities. However, confirmation of Alzheimer's disease does not occur until after death.
Alzheimer's disease is becoming more prevalent in developed nations, where an increase in the population of elder persons has occurred due in part to improved healthcare. While less than 1% of the population under the age of 60 is affected by Alzheimer's, it is estimated that 25% to 33% of persons develop some form of Alzheimer's by the age of 85. As of 2012, 5.4 million Americans were diagnosed with Alzheimer's. As life expectancy continues to increase worldwide, the prevalence of Alzheimer's and other age-related dementia will likely continue to grow as well.
Histopathologically, this neurodegenerative disease is characterized by the formation of amyloid plaques, neurofibrillary tangles, amyloid angiopathy, and granolovacuolar degeneration in the cerebral cortex (Mirra et al., Arch Pathol Lab Med., 117:132-144 (1993); Perl D P, Neurol Clin., 18:847-864 (2000)). The characteristic amyloid plaques, used to confirm Alzheimer's disease post-mortem, are formed largely by deposition of a small amyloid-beta (Aβ) peptide derived from the amyloid precursor protein (APP).
To date, the U.S. Food and Drug Administration (FDA) has approved two types of medications for the management of Alzheimer's disease: cholinesterase inhibitors, including Aricept® (donepezil), Exelon (rivastigmine), Razadyne (galantamine), and Cognex (tacrine); and the NMDA-type glutamate receptor inhibitor memantine (marketed under a number of different brands). Although a cure for Alzheimer's disease has not been identified, these therapies serve to alleviate cognitive symptoms such as memory loss, confusion, and loss of critical thinking abilities in subjects diagnosed with age-related dementia (e.g., Alzheimer's disease). In all, it is estimated that healthcare spending on Alzheimer's disease and related age-related dementias in 2012 will be $200 billion in the United States alone (Factsheet, Alzheimer's Association, March 2012).
In addition to these approved therapies, several studies have suggested that pooled intravenous immunoglobulin (IVIG) is effective in slowing the progression of symptoms in Alzheimer's patients (Dodel R C et al., J Neurol Neurosurg Psychiatry, October; 75(10):1472-4 (2004); Magga J. et al., J Neuroinflammation, December 7; 7:90 (1997); Relkin N R et al., Neurobiol Aging, 30(11):1728-36 (2008); Puli L. et al., J Neuroinflammation May 29; 9:105 (2012)).
It has long been recognized that human plasma contains anti-amyloid beta (anti-Aβ) antibodies. For example, anti-Aβ antibody activity has been detected in the blood of normal adults of various ages and patients with Alzheimer's disease (Weksler et al., Exp Gerontol., 37:943-948 (2002); Hyman et al., Ann Neurol., 49:808-810.5 (2001); Mruthinti et al., Neurobiol Aging., 25:1023-1032 (2004); Nath et al., Neuromolecular Med., 3:29-39 (2003); and Sohn et al., Frontiers in Bioscience., 14:3879-3883 (2009)). Because misfolding and aggregation of Aβ polypeptides is central to the pathogenesis of Alzheimer's disease, it is thought that anti-Aβ antibodies present in commercial IVIG preparations may be largely responsible for the positive results shown in preliminary studies on IVIG treatment of symptoms in Alzheimer's patients. Thus, a plasma-derived IgG preparation enriched in anti-Aβ antibodies is desirable.
US Patent Application Publication No. 2002/0009445, by Du and Dodel, suggests that Aβ-affinity chromatography can be used to isolate anti-Aβ antibodies from human plasma. However, human plasma is already a limiting resource in the manufacture of important therapeutic compositions, such as immunoglobulin G (e.g., IVIG or IgG for subcutaneous administration), because it is provided through donations. Thus, significant portions of available human plasma cannot be allocated for use solely in the manufacture of new plasma-derived therapeutics with lesser established commercial markets, such as polyclonal anti-Aβ immunoglobulin G. Furthermore, integration of a new affinity purification step into existing manufacturing processes for plasma-derived therapeutics (e.g., IgG) may have unforeseen consequences for the final therapeutic product or manufacturing yield. In addition to requiring a complete revalidation and possible redesign of key IgG manufacturing processes, regulatory re-approval of the manufacturing procedures from key regulatory agencies would be required.
Thus, a need remains for methods of preparing plasma-derived immunoglobulin G compositions enriched in anti-brain disease-related protein antibodies, such as anti-Aβ, anti-RAGE, and/or anti-α-synuclein antibodies from the existing supply of plasma donations. Advantageously, the present disclosure fulfills these and other needs by providing methods for manufacturing IgG compositions enriched in anti-brain disease-related protein antibodies from fractions produced during the manufacture of commercial IgG therapeutics, without disrupting and/or modifying the underlying manufacturing process.